Multiprotocol label switching (MPLS) is a technology utilized to manage traffic over a network. MPLS uses labels that are assigned to a stream of traffic to route the traffic across the network. Each node of the network supports MPLS by reviewing incoming traffic received over the network and forwarding that traffic based on its label.
MPLS networks with traffic engineering capabilities can optimize traffic engineering resource allocation for customized traffic services. In MPLS networks with traffic engineering, the primary label switch path (LSP) is set up for each customized traffic service. The primary LSP is usually calculated at the head-end node, which is the node where a path originates. The establishment of the primary LSP can be automated. The automated generation of an LSP can be done by the head-end node or a separate path computation element (PCE).
A back-up LSP for each customized traffic service is utilized in case of a failure of the primary LSP and must be configured manually. Each of the links in the back-up LSP is manually selected to construct a back-up LSP with a goal of creating a disjointed path that can be relied upon when the primary LSP is in a state of failure.
When a failure of a link occurs in the primary LSP an LSR that detects the failure initiates a protection switch, where traffic being forwarded over the primary LSP is routed onto the back-up LSP. The LSR that initiates the protection switch must generate a separate alert packet to notify each of the other LSRs in the LSP. The process of generating each packet and separately forwarding them to the respective LSRs creates latency and increases the recovery time required to complete the protection switch. As a result, traffic loss increases during the recovery time as many packets will have to be dropped while the protection switch is being effected.